Many polymeric antioxidants possess significantly higher antioxidant activities compared to corresponding small molecule antioxidants, along with improved thermal stability and performance in a wide range of materials, for example, plastics, elastomers, lubricants, petroleum based products (lubricants, gasoline, aviation fuels, and engine oils), cooking oil, cosmetics, processed food products, and the like.
The synthesis of polymeric phenol antioxidants (including sterically hindered polymeric phenol antioxidants) from substituted phenols, using a hydroxyl group protection/deprotection approach is described in patent applications to Cholli, et al., including U.S. Provisional Application No.: 60/370,468, U.S. Patent Application Publication No.: 2003/230743, International Patent Publication No.s: WO 2003/87260, and WO 2005/071005, and U.S. patent application Ser. No. 10/408,679 the entire teachings of each of which are incorporated herein by reference. These methods require multiple steps and purification of intermediates at each step. For example, WO 2003/87260 discloses a synthesis of poly (tert-butylhydroquinone) (poly(TBHQ)) that requires four separate steps, including separation of intermediate components at each step.